NMR investigation of spin correlations in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi mathvariant="normal">BaCo</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mi mathvariant="normal">As</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:math>
Bibliographic record
Abstract
We use NMR techniques to investigate the magnetic properties of ${\mathrm{BaCo}}_{2}{\mathrm{As}}_{2}$ single crystals, the nonsuperconducting end member of the Co-substituted iron-pnictide high-${T}_{c}$ superconductor $\mathrm{Ba}({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}){}_{2}{\mathrm{As}}_{2}$ with $x=1$. We present $^{75}\mathrm{As}$ NMR evidence for enhancement of low frequency spin fluctuations below $\ensuremath{\sim}100$ K. This enhancement is accompanied by that of static uniform spin susceptibility at the wave vector $\mathbf{q}$ = $\mathbf{0}$, suggesting that the primary channel of the spin correlations is ferromagnetic rather than antiferromagnetic. Comparison between the NMR Knight shift ${}^{75}K$ and bulk susceptibility ${\ensuremath{\chi}}_{\mathrm{bulk}}$ data uncovers the presence of two separate components of spin susceptibility with distinct temperature dependencies, presumably because multiple electronic bands crossing the Fermi energy play different roles in the electronic properties of ${\mathrm{BaCo}}_{2}{\mathrm{As}}_{2}$.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".